Not applicable.
The present invention relates to tamper proof integrated circuit devices.
There is a fluctuation in current whenever an integrated circuit register change state. If there is a high enough signal to noise ratio, it is possible for an attacker of a tamper proof security system to monitor the difference in a standard Idd current line that may occur when programming over either a high or a low bit. The change in Idd can reveal information about keys or data. This is obviously undesirable.
It is an object of the present invention to provide a system resistant to attack by means of monitoring fluctuations in current lines.
In accordance with a first aspect of the present invention there is provided a method of providing for resistance to attack of an integrated circuit by means of monitoring current changes in a current signal in the integrated circuit, said method comprising the step of including a spurious noise generation circuit as part of said integrated circuit for emitting electromagnetic noise and reducing Signal to Noise Ratio to obscure information in the current signal that is meaningful for the attack.
The noise generation circuit can comprises a random number generator such as a LFSR (Linear Feedback Shift Register).